As one of heat exchange elements used in air conditioning apparatuses and the like, there is a cross-flow total heat exchange element having laminated structure. In this total heat exchange element, a plurality of element forming units are laminated in predetermined directions, respectively. The respective element forming units have sheet-like partitioning members and space holding members of, for example, a corrugated shape that are bonded to the partitioning members and form paths for air flows in conjunction with the partitioning members. Corrugations of the space holding member in one element forming unit and corrugations of the space holding member in the element forming unit above or below the one element forming unit cross each other at 90 degrees or an angle close to 90 degrees in plan view. When two kinds of air flows having states different from each other, in general, two kinds of air having temperature and humidity states different from each other are fed to the path in the one element forming unit and the path in the element forming unit above or below the one element forming unit, exchange of latent heat and sensible heat is performed between these two kinds of air flows via the partitioning members.
In terms of improving heat exchange efficiency in the total heat exchange element, it is desirable to increase heat transferability and moisture permeability of the partitioning members. Therefore, the partitioning members are formed by a material having high moisture absorption or moisture permeability. For example, Patent Document 1 discloses a total heat exchanger material made of a material obtained by depositing a moisture-absorbing agent on the surface of a metal sheet or a plastic sheet. Patent Document 2 discloses a heat exchange element in which a moisture-absorbing agent is impregnated in a porous member formed by non-woven fabric, metal fiber, glass fiber, or the like to form a base material and partitioning members and space holding members are formed by a material obtained by forming a moisture permeable film on the surface of this base material.
Patent Document 3 discloses a heat exchanger in which partitioning members and space holding members are formed by a material obtained by forming a moisture-absorbing diffusion layer with fluorine or hydrocarbon resin on the surface of the porous member. Patent Document 4 discloses a total heat exchanger element in which partitioning members or space holding members are formed by a material obtained by depositing an absorptive moisture-absorbing agent on the surface of a sheet made of metal, plastic, or paper. Patent Document 5 discloses a heat exchanger in which partitioning members and space holding members are formed by a material having different contraction and expansion properties with respect to moisture on one surface and the other surface.
In these days, to realize reduction in material cost and improvement of productivity, a total heat exchange element is also developed in which partitioning members and space holding members are formed by paper having a water-soluble or non-water-soluble moisture-absorbing agent impregnated therein or deposited thereon. As the water-soluble moisture-absorbing agent, for example, alkali metallic salt such as lithium chloride or alkali metallic salt such as calcium chloride is used. As the non-water-soluble-agent, a granular solid such as silica gel, strong acid ion exchange resin, or strong basic ion exchange resin is used. A flame retardant or the like can be further added to the partitioning members and the space holding members according to necessity.
In the total heat exchanging element in which the partitioning members and the space holding members are formed by paper, element forming units are formed by bonding the partitioning members and the space holding members to each other with an adhesive. The total heat exchange element is manufactured by laminating a necessary number of the element forming units in a predetermined direction. In manufacturing the total heat exchange element, the element forming units adjacent to each other in the laminating direction are bonded to each other by an adhesive. It is possible to use both water-solvent and organic solvent adhesives for the bonding of the partitioning members and the space holding members and the bonding of the element forming units.
However, when the organic solvent adhesive is used, vaporization of an organic solvent, dissipation of odor, and the like occur from the total heat exchange element. When the organic solvent adhesive is used, complicated and expensive accessories such as an apparatus for collecting the organic solvent has to be provided in a production facility for the total heat exchange element. Because of these reasons, the water-solvent adhesive is often used in, in particular, a total heat exchange element for air conditioning apparatuses.
When the water-solvent adhesive is used, if a moisture-absorbing agent is water soluble, the moisture-absorbing agent diffuses to both the partitioning member made of paper and the space holding member made of paper via the water-solvent adhesive. Therefore, in this case, even when the water-soluble moisture-absorbing agent is impregnated in one of the partitioning members and the space holding members in advance and, thereafter, the partitioning members and the space holding members are bonded to manufacture element forming units, it is possible to obtain element forming units in which the moisture-absorbing agent is impregnated in both the partitioning members and the space holding members.    Patent document 1: Japanese Patent Application Laid-open No. S58-132545    Patent Document 2: Japanese Patent Application Laid-open No. 2002-310589    Patent Document 3: Japanese Patent Application Laid-open No. 2005-24207    Patent Document 4: Japanese Patent No. 2829356    Patent Document 5: U.S. Pat. No. 6,536,514